We propose to establish a Rare Diseases Clinical Research Consortium (RDCRC) as a part of the Rare Disease Clinical Research Network (RDCRN) that will focus on the inborn errors of heme biosynthesis, the Porphyrias. The RDCRC will initially bring together the complementary strengths of senior porphyria experts at five regional centers, the American Porphyria Foundation (APF), the porphyria patient advocacy and support group, and biopharmaceutical companies improving and/or developing novel therapies. All five centers are at academic institutions that have NIH-funded CTSAs [University of California, San Francisco (UCSF), University of Alabama, Birmingham (UAB), and the University of Utah (UoU)], or GCRCs [University of Texas Medical Branch, Galveston (UTMB), and The Mount Sinai School of Medicine (MSSM)]. The porphyria experts at these centers comprise an already interactive and interdisciplinary team of translational and clinical investigators who have active basic and clinical porphyria research programs, a strong track record for training young investigators, and internationally recognized clinical expertise. Their combined resources and expertise will advance clinical research in the porphyrias through the clinical studies and trials described in this application. We also propose to train the next generation of clinical and translational porphyria experts, supported in part by this grant and a $1 million matching grant donated by patients and industry to the APF. The Principal and Co-Principal Investigators will be Robert J. Desnick, PhD, MD, Professor and Chair of Genetics and Genomic Sciences at MSSM and Karl E. Anderson, MD, Professor of Preventive Medicine and Community Health at UTMB, respectively. The three other Con- sortium sites will be directed by D. Montgomery Bissell, MD, Professor of Medicine at UCSF, Joseph R. Bloomer, MD, Professor of Medicine at UAB, and James P. Kushner, MD, Professor of Medicine at UoU. Additional affiliate centers will be included over time as funding permits, including support from other grants and philanthropic sources.